broken yum

[Aaron Hughes <hughesac clarkson edu>]

I was updating python last night and I think I installed a version for 
fedora core test 1.91.  I uninstalled it and re-installed my old version 
python2.2.  Now whenever I try to run yum I get this error.  I have 
tried re-installing yum a couple times with different versions and I get 
the same thing everytime.  Any ideas on how to fix it.  By the way apt 
still works fine but I would rather use yum.
--chunk

# yum check-update
Could not find platform independent libraries <prefix>
Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
'import site' failed; use -v for traceback
Traceback (most recent call last):
 File "/usr/bin/yum", line 20, in ?
   import os
ImportError: No module named os